Thousands of firefighters in southern Australia were on alert Tuesday over fears that strong winds and dry conditions could whip still-burning wildfires into a dangerous new threat to residents.

More than 600 schools and child care centers were closed, as well as 30 national parks where fires could spring up, and 5 million people were sent text messages on their mobile phones warning them of the dangerous conditions.

The Bureau of Meteorology reduced its temperature forecast to 79 degrees Fahrenheit but said gusting winds were still expected across Victoria state, which has been battling several large fires for weeks. The four main fires, burning within firebreaks, have not threatened homes for days, and rain was falling in some areas Tuesday.

However, senior forecaster Terry Ryan said an expected wind change later Tuesday could bring gusts of up to 50 miles per hour.

Up to 5,000 firefighters and state emergency personnel, backed by hundreds of trucks and water-dumping helicopters, were on high alert as winds gathered pace early Tuesday.

Officials fear a new fire threat to match that of Feb. 7, known as Black Saturday, when at least 210 people were killed by fast-moving fires.

"The temperatures are milder than those on Black Saturday but those wind gusts may be stronger than what was experienced on that day," said James Todd, spokesman for the Department of Sustainability and Environment. "Winds are our main concern at the moment, coupled with the dry condition and the fact that the fires are burning in steep, difficult terrain."

Officials have urged residents to decide either to leave their homes before fire threatens or to prepare themselves to fight the fires.

On Monday, state Premier John Brumby said the weather was "unprecedented" and warned Tuesday's conditions were "up there with the very worst."

"We've got more people on the ground, more tankers, more resources, more people from interstate, more aerial appliances than we've ever had in the history of the state," Brumby said.